Automatic stitch length control mechanism for knitting machines



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Aug. 10, 1954 2,685,786

V. T. STACK AUTOMATIC STITCH LENGTH CONTROL MECHANISM FOR KNITTING MACHINES Filed Jan. 25, 1953 7 Sheets-Sheet 1 a gal) ATTORNEYS.

Aug. 10, 1954 v 1- s c 2,685,786

AUTOMATIC S TI' ICH LENGTH CONTROL MECHANISM FOR KNITTING MACHINES Filed Jan. 23, 1953 7 Sheets-Sheet 2 ="IZ1'EIIIILIZZZII I INVENTOR.

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V. T. STACK AUTOMATIC STITCH LENGTH CONTROL MECHANISM FOR KNITTING MACHINES Aug. 10, 1954 '7 Sheets-Sheet 3 Filed Jan. 25, 1953 INVENTOR. oiflasfladf,

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AUTOMATIC STITCH LENGTH CONTROL MECHANISM FOR KNITTING MACHINES Filed Jan. 23, 1953 7 Sheets-Sheet 4 INVENTOR. Va r1700 T amas fidG BY al al A TTORNEYS.

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AUTOMATIC STITCH LENGTH CONTROL MECHANISM FOR KNITTING MACHINES Filed Jan. 23, 1953 7 Sheets-Sheet 5 INVENTOR. Verna/gamma Si aciz', BY 2 p ATTORNEYS.

Aug. 10, 1954 Filed Jan. 25, 1953 V. T. STACK AUTOMATIC STITCH LENGTH CONTROL MECHANISM FOR KNITTING MACHINES UIITIHIIIIHIHE '7 Sheets-Sheet 6 ATTORNEYS Aug. 10, 1954 v, STACK 2,685,786

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Patented Aug. 10, 1954 AUTOMATIC STITCH LENGTH CONTROL MECHANISM FOR KNITTING MA- CHINES Vernon Thomas Stack, Walkertown, N. 0., assignor to Hanes Hosiery Mills Company, Winston-Salem, N. 0., a corporation of North Carolina Application January 23, 1953, Serial No. 332,800

This invention relates to stitch length or loop size control mechanism useful more particularly in connection with circular knitting machines such as are commonly used in the commercial production of seamless hosiery and the like, having a needle cylinder with a complement of independent needles and cooperative sinkers, knitting cams for actuating the needles, and means for rotating and/or oscillating the cylinder relative to the cams or vice versa. In the production of ladies hosiery by machines of the kind referred to, the boot or leg portions are shaped by gradual reduction in the size of the fabric loops as the knitting proceeds, this alteration in loop size being effected by progressively changing the vertical relationship between the needle cylinder (which carries the sinkers) and the knitting cams. However, stockings successively knitted on circular knitting machines, as ordinarily constructed, differ considerably in length due to variations in the yarns and the tension maintained thereon as it is fed to the needles, with consequent formation, in individual courses, of loops which differ in size and/ or contour causing, in addition to varying stocking lengths, streaks, shadow lines or rings which detract from the marketable value of the stockings.

The chief aim of my invention is to overcome the above mentioned drawbacks, that is to say,

to make possible successive productiom'upon circular knitting machines, of stockings which are alike from the standpoint of length, in which the loops of individual courses are regular in contour and uniform in size, and moreovenin which the loops are accurately and evenly graduated as between successive courses of the leg for attainment of perfect shaping.

These objectives are realized in practice, as hereinafter more fully disclosed, through provision of a relatively simple and reliable automa- "tic mechanism which, in cooperation with the sinkers of the knitting machine, not only functions during the knitting of'individual fabric courses to change the vertical relationship between the needle cylinder and the knitting cams by infinitesimal degrees to insure the" formation of regular loops of uniform size inindividual courses of the fabric, but also during the knitting of the leg portions of the stockings to bring about changes in the aforesaid relationship progressively to greater extents for graduationin the size of the loops as between'successive courses.

Other objects and attendant advantages will appear from the following detailed description of the attached drawings-wherein:

26 Claims.

Fig. l is a view in front elevation of a circular stocking machine with automatic stitch length control mechanism conveniently embodying my invention, a portion of the machine being broken out to expose important parts which otherwise would be hidden.

Fig. 2 is a fragmentary view of the machine in side elevation as seen from the left of Fig. 1, also with a portion broken out, drawn to a larger scale.

Fig. 3 is a fragmentary plan view, likewise on a larger scale, taken as indicated by the angled arrows III-III in Fig. ,1, in connection with which is shown a wiring diagram including an electric motor and various switch devices embodiedin the control mechanism.

Fig. 4 is a detail sectional view on a still larger scale taken as indicated by the angled arrows IVIV in Fig. 3.

Fig. 5 is a fragmentary detail view in elevation looking as indicated by the angled arrows V--V in Fig. 4.

Fig. 6 is a fragmentary view in vertical section taken as indicated by the angled arrows VI-VI in Fig. '1.

Fig. 7 is a fragmentary view in elevation looking as indicated by the angled arrows VII--VII in Fig. 6.

Fig. 8 is a fragmentary view in elevation looking as indicated by the angled arrows VIII- VIII in Fig. 1. I

Fig. 9 is a fragmentary detail view in section taken as indicated by the angled arrows IX-IX in Fig. 2 and drawn to a larger scale.

Fig. 10 is a fragmentary view in elevation looking as indicated by the angled arrows XX in Fig. 9.

Fig. 11 is a horizontal section taken as indicated by the angled arrows XIXI in Fig. 2.

Fig. 12 shows aseamless stocking blank produced in' accordance with my invention; and

Fig. 13i'sa view like Fig. 3 showing an alternative'control circuit.

The .machine chosen for convenience of exemplifying my invention is of the wellknown Scott and Williams. type whereof the rotary needle cylinder I5 is mounted, with capacity for,

slight independent up and down axial movement, upon" a bevel gear I6 which is recessed for rotation in a bed I! at the top of the machine frame l8. Gear I6 is in mesh with a bevel gear I9 on main shaft 20 which carries the high speed, low speed and loose pulleys 2|, 22 and 23 respectively. The shipper 25 for the belt '26 is mounted as usual 'on a slide bar 21 whereto is secured the shifter fork 28 for the clutch collar 29, said-fork being controlled from the main timing drum 38 for impartation of oscillatory movements of the needle cylinder during the heel and toe knitting phases, and said drum being intermittently shogged about through a complete revolution for each knitting cycle of the machine in a well known manner. ing receiving column or tube, designated til in Figs. 1 and 2, engages upwardly with a-slide fit into a pendent boss Ila of bed I1; and interposed between the top of said tube and the bottom of needle cylinder I5, is a plurality of annularly spaced upright pins 4| which are axially slidable in the bevel gear I5 and upon which the cylinder rests. Accordingly, by up or down movements imparted to tube M3 and cylinder I5, and hence to the sinkers S (Figs. 3 and 4) carried in the sinker ring 42 around the upper end of said cylinder, are raised or lowered by corresponding amounts, with consequent lengthening. shorting fabric loops as well understood in the art. For the purpose of producing vlongwelt top ladies stockings, the machine is provided with the usual welting dial .5 which is positioned within the upper end of cylinder I5. Thedial 45 is rotated in unison with needle cylinder I 5 by a drive system including another bevel gear 46 on pulley shaft 20, which meshes witha bevel pinion 41 at the lower end of a vertical shaft 48 rotatively borne in afixed upstanding post 49 on bed 17. A bevel pinion 50 atthe upper end of shaft 68 meshes with a bevel wheel 5! at outer end of a horizontal shaft 52 rotatively supported in a bracket 53 on the usual needle latch guard ring 55 of the machine. A bevel pinion 5B=at the inner end of horizontal shaft fizmeshes in turn with a bevel gear 51 at the top-end of the shaft 58 of welting dial 45, the latter shaft being also rotatively supported in bracket 53. The machine is also provided in this instance with a patterning drum 59 for selecting individual needles for tucking or other special stitching. The knitting cams (not shown) are mounted within a ring 60 on a circular bed fiI sustained at an elevation above bed I! by columns 62, and the supplemental timing drum 63 of the machine is intermittently rotated with main drum 3Il:through gearing 64, from the shaft 68 of the latter drum.

In adapting a knitting machine, such as above briefly described, to the purposes of my invention, I utilize a reversible electric motor 10 (Figs. 1, 2, 3 and 11) as a source of power for raising and lowering the needlecylinder I5 to vary the size of the fabric loops incident to knitting stocking blanks shaped as shown in Fig. 12, said motor being supported by a fixed bracket bolted to the base of the machine frame 58. Through speed reducing worm gearing ii, the motor Ill drives a finely threaded vertical axis screw 12 which engages into a tapped lateral lug projection 53 adjacent the bottom end of tube 43 and which is adapted to react upon a push block I4 on the base of the machine. During each stocking knitting cycle, theoperation of motor iii iscontrolled by a reversing detector switch comprehensively designated 75. As bests-hown in Figs. 8, i and 5, this switch includes a slide l6 whichis constrained to movement radially of needle cylin- The usual non-ratating stock.-.

der if; at the level of the sinker cam ring 36 in a guide bracket 5'! affixed to post 59. Fulcrummed on upright pivot stud 58 at the inner end of slide 76 is a meinber 153 with yoke projection 36in which is secured a pivot stud 8| in axial alignment with stud i8. Supported, with capacity for independent swinging-movement between the inner ends of the studs l8 and BI, is a contact finger 82 which is formed with a rearward projection 83 that bears against the outer convex edge of, a rider element 8 3 fulcrummed at 85 within-a slot iii; in the sinker cam ring 36, see Fig. 4, the inner edge of said rider element bearing, in turn, against outer ends of the sinkers S. A stop in 8'! (Fig. 3) serves, by cooperation with a notch 88 in the distal end of the rider element 84, to limit the extent to which the latter can be moved. Springs respectively designated 3% and 9;), tend to move the arm I9 andiinger arm 8-2 clockwise independently about their common pivot axis. Normally, contact fin ger 82 occupies the neutral position in which it is shown in Fig. 3, with its distal end midway between and clear of a pair of opposedly arranged contactsfli and 92 which are adjustably engaged in the upstanding side. portions 93 of a bracket 9 1 of a dielectricmaterial secured upon the outer end portion of arm I9. Guided in a vertical groove 95 in bracket 11 is a wedge cam 95 .which is adapted to act upon a screw stud 9? adjustable in a lateral lug projection 98 on slide It to shift the latter outward, at times as later on explained, against the pull of the: spring shown at 99 in Figs. 4 and 5,, one end of said spring being anchoredto a pendent projection II!!! at the outer end of said slide.

Through a Bowden wire mi confined in a guide sheathing I02, affixed at I03 to the edge of bed SI (Fig. 1) andatlll to the projection I85 of a bracket I06 (Fig. 2) at the base of the machine frame I8, the wedge cam 96 is. shifted up or down by the graduating mechanism comprehensively designated I It in Figs. 1, 2 and 9. As shown, this graduating mechanism Iiil includes a bell'cranklever Ii! which is fulcrumed at M2 on bracket Hi6. Aspring 1 I3 in tension between the bracket projection I05 and one arm of bell crank lever I I I, yieldingly urges said lever counterclockwise inFig. 2. Adjustable in the other arm of bell crank lever I l Iare three screws H5, IIB-and II"! (see Fig. 9), which are adapted to respectively engage, at different times, the pe ripheries of three cam ridges II 8, H9 and E26. As shown in Figs. 2, 9 and 10, the cam ridges H8, H9 and I25 aresecured, by screws I25, to one side face ofa ratchet wheel I22 mounted at the left hand endof the shaft 68 (Fig. 1) of main timing drum 36. From Fig. 10 it will be observed that the curvature of cam ridge is spiral or eccentric to the axis of drum shaft '53. Extending laterally from the outer face of cam ridge H8 is a stud 526 which lies in the path of thefinger projection I2! of a disk I 28 secured, with capacity for circumferential adjustment, to the corresponding end of drum shaft E8. Ratchet wheel 22 is arranged to be picked by a pawl I tfipivotally connected at I 3I to an arm i2 2 fulcrumed on a fixedpivot 33 at the base of frame I8, said arm being rocked by a roller I34 on the usual constantly moving gear quadrant I35 through which the needle cylinder I 5 is oscillated during the heel and toe phases of the stocking knitting cycle. Pawl 53-9 is yieldingly urged upward by the spring shown at 538 in Fig. 2, with its end normally playing idly 0n the toothless void 53? of ratchet Wheel 5232, which latter is frictionally restrained against overthrow by a spring tongue I38. For a reason later on pointed out, movementof the bell crank lever i i I in one direction is restricted by engagement of an adjustable screw I39. on its tail end with a stop Mil on the projection-I 05hr bracket H15.

During the knitting of the heel and toe pockets of the stocking, detector switch mechanism is -retracted by means of an upright lever IM medially fulcrumed at I42 at the edge of the top plate of the machine frame I8, see Fig. 1.

AS shown, the lower end of lever MI is in the path of a stud projection I43 on the clutch shifting arm 28, and the upper end of said lever extends to the rear of the pendent lug I08 on the slide 16 of detector switch mechanism 15. Moreover, :during heel and toe knitting, the size of the fabric loops is determined in the usual manner through tively on the periphery of auxiliary timing drum 63, and at an intermediate point, said arm carries another adjustable screw I 5| which bears upwardly upon a lateral lug projection I52 on stocking receiving tube 40.

In addition to the detector switch mechanism 15, 1 have provided safety'switches I55 and I56 =(Figs. '1, 2 and 11) which are actuated by a lug projection! 51 On the tube 49 to interrupt current :fiow to the motor 19 thereby to prevent raising or lowering of said column beyond predetermined limits; a master switch I58 (Figs. 1, 6 and 7) which is normally closed but which opens automatically when the machine stops; a switch-I66 (Figs. 1, 2 andil) adapted to be actuated by a stud'I6I on worm wheel 1|; a switch I62 (Figs. 1 and 8) adapted to be actuated by the lateral projection on a supplemental cam disk I68 on shaft 68 of main timing drum 38; and a circuit breaker or switch I65 (Figs. 1 and 2) adapted to "be actuated by a lateral cam projection I66 on the supplemental timing drum 63.

As shown in Figs. 6 and '7, master switch I58 is supported by a post I65 upstanding from the top plate of the machine frame, and its movable :contact I66 is arranged to be actuated by a fly ball governor I61 at the-upper end of a vertical shaft I68 rotatively supported in a bearing bracket I69 affixed to the rear of said frame. Through 'a pair of intermeshing'bevel bear pinions I10, "shaft I68 isdriven from a horizontal shaft I1I also journalled in bracketi69, the latter shaft having, at its inner end, a spur pinion I12 in mesh with the usual segment driving gear I13 of the machine.

"The motor and the several switches are em bodied, as. diagrammatically illustrated in Fig. 3,

'of -fractional horse power motors. switches etc; For the purposes of exemplification, A. C. current :at 115 volts delivered to transformer T is'stepped down to say 24 volts for use in the motorcircuits. As shown in'Fig. 3, switchI62 is interposed in a conductor I14 which leads from one terminal of the secondary of transformer T tothe terminal C of motor 10. Through a conductor I15, the terminal R of motor 16 is connected to the movable contact I16 of the up limit switch I55, thestation'ary contact I1 1 of the latter being in turn connected by a conductor I18 to the movable contact 1190f circuit breaker I 65. Another conductor I86 connects the I fixed contact I8I of switchI65 to "the fixed contact 9I. of detector switch 15. Leading from the pivot 8I of the detector switch finger 82 is a conductcr I82 which extends to the other terminal of the secondary coil of transformer T. Through a conductor I83,

the terminal L of motor 19 is connected to the movable contact I85 of circuit breaker I65, the stationary contact I86 of which latter is connected by a conductor I31 to the fixed contact I88 of down limit switch I56. As further shown, the movable contact I89 of the down limit switch I56 is connected by a conductor I90 to the fixed contact 92 of detector switch 15, and a conductor I9I connects the movable contact I92 of switch I66 with the movable contact I93 of circuit breaker I65. As further shown, the fixed contact I95 of switch I66 is connected by a conductor I96 to conductor I82. Master switch I58 is interposed, with the primary of transformer T, in power circuit M, MI.

Operation Let it be assumed that the machine is dormant in Fig. 1, with belt 26 on idling pulley 23; with the tubular column 40 (and needle cylinder I5) in highest position; with screw I I5 (Figs. 2, 9 and 10) on arm III resting upon cam H8; and with pawl I90 riding idly upon the void I31 of ratchet wheel I22, all in readiness for the formation of fabric loops of maximum size. As belt shipper 25 is shifted to transfer belt 26 to high speed pulley 2I ,the machine is started for rotary knitting, incident to which master switch I58 is closed by the action of ball governor I61 as in Fig. 3. Fabric for the welt top W of the stocking (Fig. 12) will then first be formed, and, upon its completion, the welt will be closed at the course I-I in the usual well known manner. If, during this phase of the knitting, the fabric loops should tend to tighten due to tension variations or inequalities in the yarn as it is fed to the needles, the sinkers S will move outward, such movement is communicated, through rider element 84 (Fig. 3), to finger 82 of detector switch 15 whereby the said finger will be swung counterclockwise into engagement with contact 6|. As a consequence,

" electric current will flow from terminal t of the vate tube 68 and needle cylinder I5 to the extent necessary for loop equalization. If, on the other hand, the fabric loops should tend to slacken or increase in'size, rider element 84 will move inwardwith the sinkers S, with attendant swinging of the finger 82 of detector switch 15 clockwise in Fig. 3 by spring 96 into engagement with contact 92." When this happens, electric current will flow from'terminal t of the secondary coil of transformer 'If .through conductor I82, finger'BZ of detector switch 15, contact 92, conductor I90,

closed contacts I89, I88 of down limit switch I56,

7 closing of the stocking welt W at. course i-l (Fig. 12), ratchet wheel I22 is turned clockwise slightly to bring cam i I9 thereon into the range of screw IIii on bell crank lever I I I, which latter will thereby be moved counterclockwise slightly by the pull of spring I I3 (Fig. 2) with the result thatthrough Bowden wire ml, wedge 96 (Fig. 4) wih be shifted upward by a proportionate degree to correspondingly retract slide 76 of detector switch by a small distance and thereby bring about a small decrease in loop size for the knitting of the shadow welt W of the stocking (Fig. 12) As slidelt isgso shifted, finger 82 of detector switch T5 (Fig. 3) will be swung by spring 90 into engagement with contact 9! so that the current will flow through coil L-C' of motor If! to rotate the latter momentarily in the proper direction to lower tube 10 and needle cylinder to, the extent required for the formation of somewhat smaller loops, whereupon the finger 82 of detector switch 5 will resume the normal neutral position in which it is shown in Fig. 3. Upon completion of the shadow welt W (Fig. 12) at the course 2-2, drum shaft :68 (Figs. 2,9 and 10) is given another rotative shog to bring the point a: of cam I into, the range of screw Ill on bell crank lever III, whereby detector switch I5 is re-set as before to determine the formation of still smaller loops during the knitting of the uniform diameter upper portion of the stocking boot to course 3--3. At course 3-3, the shaft 68 of main timing drum shaft .68 is given another rotary shog to bring the first tooth I220: of ratchet wheel I22 into the range of pawl I38. From then on, as screw II'I rides upon the eccentric cam I20, bell crank lever III will move counterclockwise incrementally as ratchet wheel I22 is picked and wedge cam 96 (Figs) will be correspondingly raised, step by step, through the medium of Bowden, wire I81, with the result that the fabric loops will be gradually decreased in size by progressive lowering of tube 40 and needle cylinder I5. The stocking leg will thus be tapered as shown in Fig. 12 to the course 4-4 which will be formed of loops of minimum size. By the time course 4-4 is reached, ratchet wheel I22 will have been picked through a distance such that the point y of cam IE0 is presented beneath screw I ll. onbell crank lever Ill, whereafter the stitch size during the knitting of thestocking ankle A to the course 51-5 in Fig.12, will be determined by engagement of screw I39 on bell crank lever I I I with the stop I40 (Fig. 2) on bracket I86. In the interim, ratchet wheel I22 will be picked idly untilit reassumes the normal dormant position .in which it is shown in Fig. 10, in which positionit will remain until called upon to function again for the next stocking. Thereupon, by another rotary shogof main timing drum 36 at the course 5-5, fork .28 (Fig. 1) is moved leftward to shift clutch 29 for initiation of an oscillatory phase of the machine to knit the stocking heel H in the usual way. Through movement of fork. 28 as just explained and attendant actuation of lever I4I, detector switch I5 is retracted from rider element '8 to leave the sinkers S free, and therefore does not. function during heel knitting, the motor circuits in Fig. 3 having been opened by rise I63a of cam Its incident to the last mentioned rotary shog of main timing drum shaft 58. During the heel knitting, the stitch length is determinedby auxiliarytiming drum 63 through conventional stitch regulating lever M5 and action of cam lug I49 against screw [ill (Figs. 1 and 2). By an other rotaryshog of main timing drum 30 upon completion of the stocking :hee-l at the course 6--"I Fig. 12, fork 28 is shifted rightward to the position of Fig. 1., to bring, the machine back into rotation incident to which detector switch i5 is returned to the active position of Fig. .3 by spring 99 (Fig. 4) in readiness to operate during knitting of the stocking instep I. As this stage of the knitting isinitiated, switch I152 is closed by rotary advance beyond it of the rise 16301. of cam I63 to re-establish the motor circuits, the size of the loops being here determined in the same way as described in connection with the knitting of the ankle A. For the knitting of the advance toe ring U (Fig. 12), auxiliary timing drum 63 is given another rotary shog whereby its cam proiection I56 is advanced beneath adjusting screw M9 on conventional stitch regulating lever M5 to position tube 40 and needle cylinder I5 as was previously done in preparation for heel knitting. At thecompletion of the toe ring U, timing'drums 3i) and 63 are again rotatively shogged whereby the machine is-once more set into oscillation for the knitting of the stocking toe pocket P, detector swich I 5 being incidently retracted to inoperative position and switch I62 opened by advance thereto of the rise 1153b of cam 1'53, and column 40 positioned with needle cylinder by advance of cam projection I49a on drum 63 beneath screw M'I- of the conventional stitch regulating lever I45. Upon. completion of the toe pocket at the course 9-9, a few run-01f or ravel courses L are knitted, incident to which the size of. the loops is still determined by cam projection 490, on auxiliary oamdrum. Since, at this time, the height of cylinder I5 willv be above that at which the foot was. knitted, the lower end of jack screw M (Fig. 2) will be above push block 14. Accordingly, it is necessary at this point to run. motor in inv clockwise direction to lower jack screw I2 tosuch position. that when the run offis finished and cam. projection "96L on drum.63 is advanced froinbeneathlever I45, said screw will be adjusted. correctly. for beginning the welt of new stocking. This resetting of jack screw 12 is accomplished as follows:. As auxiliary drum 63 is given the rotary shog at. the beginning of the run-off, camprojection. IBB. thereon is advanced to open the contacts of. circuit breaker I65 to break the circuit connections between motor 10 and detector switch "I5. By this action, contact I19 is moved into engagement with contact I93 so that raising coil 3-0 of motor III. is still energizedthrough gear limit switch ISO to rotate jackscrew I2.clockwise.until stud IBI on worm wheel TI engages the movable. contact of said switch and opens it to stop said motor. Stud IBI is so locatedon worm wheelII that switch 'Ifill isopened when screw 12 has been rotated to correctly position tube .49 and needle cylinder I5 to determine the loop size for the welt of the next stocking. When drum '63. receives its final rotative shog at the end of. the stocking knitting-cycle, cam lug Ifit is advanceclbeyond operatinglever of circuit breaker I65 to allow openingof contacts IlS'and I93 and reclosing of contacts H9, I81 and I85, I86, whereby. themotor circuits are reset to the. condition of Fig. 3. As has already been pointed out hereinbefore, the limit switches I55 and [58 are relied upon to open the motor. circuit in the event that motor It should accidentally overrun ineither direction. In this way-the entire mechanism is protected against derangement and possibleinjury.

From the foregoing it will be realized that detectorswitch liiwill open and close many times ,9... during the knitting of a. stocking in compensating for variations in yarn tension and in yarn size, and also incident to loop length changes as the stocking leg is being fashioned. In the basic diagram of Fig. 3, detector switch I is directly interposed in the reversing circuits of the motor Ill, and is thus called upon to make and break the current supplied to the motor at full load at a relatively high potential--in the present expair of power relay switches 2G2, 202a. Finger 82 of detector switch I5 is connectedithrough conductors 203 and 264 to main M of the power line, and contacts 9| and 92 of said detector switch are connected, by conductors 206 and 205a, to the grids of tubes 200 and 200a. The coils of relay switches 2M and 20|a are interposed in the cathode plate circuits 201, 208, 298a and 201a of tubes 206, 288a, conductors 2M, 201a, and are energized from the power line through conductors .269, 2% and 2|!) respectively. Conductors 2H and 2| Ia leading from the contacts of plate relay switches 29!, 2am are connected'through conductors 2I2 andZIB, to the main M of the power line. As further shown, the coils of power relay switches 2512 and 2920, are connected by conduo tors 2 I 3 and 2 I 3a which, through a conductor2 I 5, are connected to conductor 209; The fixed contacts of power relay switches 292, 2020, are connected by conductors 2 I 6 and 2 I 6a which, in turn, are connected by a conductor, 2II to terminal t of the secondary coil of transformer T. The movable contacts of power relay switches 202 and 20211 are similarly connected respectively, through conductors 2H? and 2I9, to the contactsISl and I89 of switches I65 and I56 of the motor circuits which latter are otherwise identical with those of Fig. 3. Accordingly, in order to obviate the neoessity for repetitive description, the component elements of the motor circuits in the alternative arrangement of Fig. 13 areidentified by the same reference numerals previously employed. I

The operation of the alternative embodiment is as follows: Let it be assumed that finger 82 of detector switch I5 has been moved into engagement with the fixed contact 9| of said switch. As a result, tube 299 will be fired by current flow from the power mains M, M through circuit 204, 203, 82, 9|, 296, 20! and 2m, and thus permit current flow,in turn, in the cathode plate circuit 204, 2G9, 298, 201 and 2m of said tube. Through attendant closing of plate relay switch 2!, circuit 204, 209, 2I5, H3, 2, 2I2 and 2H] will be established through the coil of power relay switch 202. Current will thereupon flow from the secondary coil of transformer T through conductors ZI'I, 2|6, 2|8, I78, I75 coil C-R of motor I0 closed switch I62 and conductor I14, and accordingly, said motor will be driven in one directionuntil finger 82 of detector switch is returned to its normal neutral position between contacts 9| and 92. In a similar manner, upon movement of finger 82 into engagement with contact 92, tube 208a will fire, with attendant closing of plate and power relay switches 20m, 202a and with estab= lishment of the circuit through coil CL of motor 10 whereby said motor is driven in the opposite direction, current flow in the latter instance being from the secondary of transformer T by way of conductors 2H, ZIfia, 2|9, I81, I83 coil C'L, closed switch I62 and conductor I'M. Since the grid currents of tubes 2% and 280a broken by detector switch are very small, it will be evident that the life and sensitivity of the contacts of said switch will be longer as compared to those in the arrangement of Fig! 3. The size and type of the'contacts of power relays 252 and 282s will be selected, of course, to carry the required value of motor current at the interrupt-- ing frequency necessary.

Having thus described my invention, I claim:

1. Automatic stitch length control mechanism for a knitting machine having a grooved carrier with a complement of independent needles and supporting a complement of cooperative slide sinkers, and knitting cams for actuating the needles', said mechanism including'reversible motor means for moving the carrier and the knitting cams relatively to increase or decrease the distance between the sinker level and the cams; and a detector means influenced by the sinkers for. governing the motor means to so move the I carrier and the cams relatively and thereby compensate for irregularities in the yarn or in the tension thereon as it is fed to the needles for maintenance of uniform loop size in individual courses of the fabric produced by the machine.

2. The invention according to claim 1, further including means for bodily moving the detector means either toward or from the carrier to effect each time, through the governing means, a

greater movement as between the carrier and the cams and,'in turn, a corresponding change in the size of the loops for different individual courses of the fabric.

3. The invention according to claim 1', further including means for periodically moving the detector means bodily either toward or from the carrier to effect, through the governing means, greater movements as between the carrier and the cams and, in turn, corresponding changes in the size of the loops for different individual courses of the fabric.

4. The invention according to claim 1, further including means for periodically moving the detector means bodily either toward or from the carrier but always in one direction, to effect,

through the governing means, greater movements as between the carrier and the cams and, in turn, corresponding changes in the size of the loops in successive courses of the fabric.

5. Automatic stitch length control mechanism for a knitting machine having a grooved cylinder with a complement of independent needles and supporting a complement of cooperative slide sinkers, and knitting camsv for actuating the needles, said mechanism including a detector means influenced by the sinkers in the event of any tendency of the fabric loops to tighten or slacken; and means governed by the detector means for changing the vertical relationship between the needle cylinder and the knitting cams as may be required for maintenance of a uniform loop size in individual courses of the fabric produced by the machine.

6. The invention according to claim 5, further including means for bodily moving the detector means radially toward or away from the needle cylinder to efiect, through the governed means, a greater change in the vertical relationship between the needle cylinder and the knitting cams 11 and, in turn, a corresponding change in the size of the loops for individual courses of the fabric. 7. The invention according to claim 5, further including means for bodily moving the detector either toward or away from the needle cylinder to efiect each time through the governed means, a greater change in the vertical relationshipbetween the needle cylinder and the knitting cams and, in turn, a corresponding change in the size of the loops for different individual courses of the fabric.

} 8. The invention according to claim 5, further including means for bodily moving the detector means periodically either toward or away from the needle cylinder but always in one direction to effect each time through the controlled means, a greater change in the vertical relationship between the needle cylinder and the knitting cams for graduation of the size as between successive courses of the fabric as it is being knitted.

9. Automatic stitch length control mechanism for a Knitting" machine having a cylinder with a complement of independent needles, a complement of cooperative slide sinkers supported by the cylinder Knitting cams for actuating the needles, said mechanism including detector means influenced by the 's'inkers in the event of any tendency of the fabric loops to tighten or slaclren, and means governed by the detector for axially moving the cylinder up or down relative to the knitting cams as may be required for maintenance of a u-niform loop size in individual courses of the fabric produced by the machine.

10. The invention according to claim 9, -furthe r including timing means for shifting the de tector means bodily award. or away from the cylinder radially to effect each time a greater axial movement of the cylinder relative to the cams and, in turn a corresponding change in the size of the loops for different individual courses of the fabric. V A a V 11. Automatic stitch length control mechanism for a kitting machine having a grooved cylinder with a complement of independent needles and a complement of coopera'tive slide sinkers supported by the cy1inder,and knitting cams for actuating the needles, said mechanism including a reversible. electric motor; interposed means actuated by the motor for changing the vertical relationship between the cylinder and the knitting cams; a normally open reversing detector switch in circuit with the motor influenced by the sinkers to cause the motor to be driven in one direction or the other. as may be required for maintenance of uniformloop size in individual courses of the fabric produced by themae chine. M

12. The invention according to claim 11, further including means forbodily moving the detector switch radially either toward or away from the needle cylinder to effect, through the motor; a greater change in the vertical relation'e ship between the-needle cylinder and the knitting cams and, in turn, a corresponding change in the. size of the loops for different individual courses of the. fabric.

13. The invention according to claim. 11, further including means for bodily moving the detector switch radially either toward or away from the needle cylinder periodically but always in one direction to enact each time, throughthe motor, 'a greater change in the vertical relation ship between the needle cylinder and the knitting cams and, in turn, a corresponding change 12 in the size of the loops in successive courses of the fabric.

14. stitch Iengthcontrol mechanism for a circular knittingmachine having cylinder with a complement of independent need1es and a complement of cooperative radially sliding sinkers supported by the cylinderand knitting cards for actuating the needles, said mechanism including a reversible electric motor; interposed means actuated b the motor for changing the vertical relationship between the cylinder and the knitting cams; a rider element engaged with the sinkers; a normally open reversing detector switch in circuit with the motor and having its actuating member bearing against the rider element whereby, as the switch is shifted toward the cylindeifl the motor is momentarily rotated in one direction and whereby when the switch is shifted away from the cylinder, the motor is momentarily driven in the opposite direction for maintenance of a uniform loop size in individual courses of the fabric producedjb'y the machine.

15. Stitch lerig'thQcontrol mechanism for a circular knitting machine according to claim 14,

further including means for moving the detector switch bodily toward or away from the cylinder to effect through the motor greater relative movements as between the cylinder and the cams and a corresponding increase or decrease. in the size of the loops in individual courses of the fabric produced by the machine.

16. Stitch length control mechanism for a circular knitting machine according to claim 14, further including spring means tending to retract the. switch relative to the rider element; a wedge cam. for restraining the switch; and means for moving the wedge cam in one direction or the other whereby the switch is bodily shifted correspondingly to effect, through the motor, greater relative movements as between the cylinder and the cams for increase or decrease in the size of the loops in individual courses of the fabric produced by the machine.

17. Stitch length controlmechanism for a circular knitting machine according to claim 14, further including spring means tending to retract the switch relative to the rider element; a wedge cam for restraining the switch; and means for periodically moving the switch cam in one direction whereby the switch is correspondingly shifted bodily to effect, through the motor; greater relative movements as between the cylinder and theknitting cams for progressive graduation of the.- size of the loops as between. successive courses of the fabric produced by the machine.

18. Stitch length control mechanism for a circular knitting machine having a grooved rotary cylinder with. a complement of independent needles and a complement: of cooperative slide sinkers constrained to radial movement in a ring on the cy-lindenstationarily. supported cams for actuating. the. needles, and avertically movable fabric receiving tube atop of which the cylinder is sustained. said mechanism including a vertical axis jack. screw in threaded engagement with a lateral lug. projection on; the fabric receiving tube; a reversible motor for rotating the jack screw; and a deteetor'means influenced by the sinkers in the event of any tendency of the fabric loops to tighten or slacken'; and interposed means by which the motor is caused to rotate one direction or theother and thereby raise or lower the fabricreceiving tube and the needle cylinder together, through the jack screw,

as may be required for maintenance of uniform loop size in individual courses of the fabric produced by the machine.

19. Stitch length control mechanism for a circular knitting machine according to claim 18, wherein the bottom end of the jack screw bears upon a fixed part of the machine; wherein a worm wheel at the top of said screw is in mesh with a worm on the shaft of the motor; and wherein the motor is fixedly supported.

20. Stitch length control mechanism for a circular knitting machine according to claim 18, wherein the motor is of a reversible electric type, and wherein the detector means is in the form of a reversing switch in circuit with said motor.

21. Stitch length control mechanism for a circular knitting machine according to claim 18, wherein the motor is ofa reversible electric type, and wherein the detector means is in the form of a reversing switch in circuit with the motor, and further including means for shifting the switch bodily toward or away from the needle cylinder by greater amounts to effect through the motor and the jack screw correspondingly greater up or down movements of the cylinder and increase or decrease in the size of the loops in individual courses of the fabric.

22. Stitch length control mechanism for a circular stocking knitting machine having a grooved cylinder with a complement of independent needles and a complement of cooperative slide sinkers constrained to radial movement in a ring around the cylinder, stationarily supported cams for actuating the needles, means for rotating and oscillating the cylinder, means by which the cylinder is sustained with capacity for up and down movement relative to the cams; means for holding theeylinder at a definite level to determine the size of the fabric loops during knitting of the heel and toe pockets of a stocking, said mechanism including a detector means influenced by the sinkers in the event of any tendency of the fabric loops to tighten or slacken during the rotary phases of the knitting; a reversible motor means'governed by the detector means for moving the cylinder up or down to the extent necessary for maintenance of uniform loop size in individual courses of the fabric during the rotary phases of the knitting; and means for retracting the detector means to prevent it from functioning during the oscillatory phases of the knitting.

23. Stitch length control mechanism for a circular stocking knitting machine according to claim 22, wherein the detector means is in the form of a reversing switch; wherein the motor means is in the form of a reversible electric motor in circuit with the detector switch; and further including a normally closed out out switch also interposed in the circuit, and means for opening the cut out switch incident toretraction of the detector means to prevent it from functioning during the oscillatory phases of the knitting.

24. Stitch length control mechanism for a circular stocking knitting machine according to claim 22, further including means for bodily moving the detector means periodically relative to the needle cylinder to effect each time, through the governed means, a greater axial movement of the cylinder for progressive decrease in the size of the loops in successive courses of the fabric during the knitting of the boot portion of the stocking.

25. Stitch length control mechanism for a circular stocking knitting machine according to claim 24, wherein the detector means is in the form of a reversing switch; wherein the motor means is in the form of a reversible electric motor in circuit with the detector switch; and wherein the means for bodily moving the detector switch periodically comprises a shiftable wedge cam against which said switch is yieldingly urged by a spring, and an intermittently rotated spiral cam with a follower bearing thereon, and an interposed actuating connection between the finger and the wedge cam.

26+ Automatic stitch length control mechanism for a knitting machine having a cylinder with a complement of needles and with a complement of slide sinkers, and knitting cams for actuating the needles, said mechanism including a reversible A. C. electric motor with forward and reverse drive coils; interposed instrumentalities actuated by the motor for changing the vertical relationship between the cylinder and the knitting cams; a normally open reversing detector switch having a finger which, under the influence of the sinkers, is adapted to be moved into engagement with one or the other of a pair of contacts, said finger being connected to one side of an A. 0. power line; normally open relay switches interposed with forward and reverse drive coils of the motor, in separate circuits energized from the secondary coil of the transformer in the power line; a pair of gaseous grid-controlled electron tubes with their cathodes and plates respectively in separate circuits pose set forth.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,516,535 Stack July 25, 1950 2,613,692 Anderson Oct. 14, 1952 

